16.This day the Lord thy God. He again reminds them that God is the author of the Law, in order that His majesty should the more impress them; and not only so, but that, since the Law was specially delivered to them, its observation was the more enjoined upon them. Hence he exhorts them earnestly to apply their hearts to those things which God had enjoined them to keep, because men grow careless in their duties, unless they are often stirred up. For, undoubtedly, God indirectly rebukes the people’s indifference, by so often calling them to obedience. By the words “with all thy soul” is meant serious apprehension, and carefulness, as well as sincerity, free from all disguise and deceit. For nothing is more displeasing to God than hypocrisy, because He seeth the heart. If any object that it was vain to demand of them what no mortal can perform, viz., to keep the Law with all their heart, I reply, that all the heart is opposed to a double or divided heart, and is equivalent to entire, or altogether without deceit, although (as we shall hereafter see) it is not absurd to propose to believers an object, at which they are to aim, although they may not attain to it as long as the weakness of the flesh hinders them.

17.Thou hast avouched the Lord231
He shews them from the consequence that nothing can be better or more desirable for them than to embrace God’s Law; for nothing can be more honorable to ourselves than to give to God His due honor, and to exalt His glory to its due preeminence. Moses declares that, if the Israelites submit themselves to the Law, this will be, as it were, to place Him in His rightful dignity; and he promises that the fruit of it will return to them, for that God, on his part, will exalt them, so that they shall far excel all other nations; as it is said in Isaiah, (Isa. 8:13, 14,) “Sanctify the Lord of hosts — and he shall be for a sanctuary.” For no otherwise does He desire to be glorified by us, than to make us in turn partakers of His glory; and thus Moses gently entices them to receive the Law, because their solid happiness consists in this pious duty, if they altogether devote themselves to obedience. But this excellency of the Church, although it shines forth in the world, is still hidden from the blind, and, since it is spiritual, only obtains its praise before God and the angels.